// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package filters

//var (
//	deadline = 5 * time.Minute // consider a filter inactive if it has not been polled for within deadline
//)

// filter is a helper struct that holds meta information over the filter type
// and associated subscription in the event system.
//type filter struct {
//	typ      Type
//	deadline *time.Timer // filter is inactiv when deadline triggers
//	hashes   []common.Hash
//	//crit     FilterCriteria
//	//logs     []*types.Log
//	s *Subscription // associated subscription in event system
//}

// PublicFilterAPI offers support to create and manage filters. This will allow external clients to retrieve various
// information related to the PalletOne protocol such als blocks, transactions and logs.
//type PublicFilterAPI struct {
//	backend Backend
//	mux     *event.TypeMux
//	//quit      chan struct{}
//	chainDb   ptndb.Database
//	events    *EventSystem
//	filtersMu sync.Mutex
//	filters   map[rpc.ID]*filter
//}
//
//// NewPublicFilterAPI returns a new PublicFilterAPI instance.
//func NewPublicFilterAPI(backend Backend, lightMode bool) *PublicFilterAPI {
//	api := &PublicFilterAPI{
//		backend: backend,
//		mux:     backend.EventMux(),
//		chainDb: backend.ChainDb(),
//		events:  NewEventSystem(backend.EventMux(), backend, lightMode),
//		filters: make(map[rpc.ID]*filter),
//	}
//	go api.timeoutLoop()
//
//	return api
//}
//
//// timeoutLoop runs every 5 minutes and deletes filters that have not been recently used.
//// Tt is started when the api is created.
//func (api *PublicFilterAPI) timeoutLoop() {
//	ticker := time.NewTicker(5 * time.Minute)
//	for {
//		<-ticker.C
//		api.filtersMu.Lock()
//		for id, f := range api.filters {
//			select {
//			case <-f.deadline.C:
//				f.s.Unsubscribe()
//				delete(api.filters, id)
//			default:
//				continue
//			}
//		}
//		api.filtersMu.Unlock()
//	}
//}
//
//// NewPendingTransactionFilter creates a filter that fetches pending transaction hashes
//// as transactions enter the pending state.
////
//// It is part of the filter package because this filter can be used through the
//// `eth_getFilterChanges` polling method that is also used for log filters.
////
//// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_newpendingtransactionfilter
//func (api *PublicFilterAPI) NewPendingTransactionFilter() rpc.ID {
//	var (
//		pendingTxs   = make(chan common.Hash)
//		pendingTxSub = api.events.SubscribePendingTxEvents(pendingTxs)
//	)
//
//	api.filtersMu.Lock()
//	api.filters[pendingTxSub.ID] = &filter{typ: PendingTransactionsSubscription, deadline: time.NewTimer(deadline),
//		hashes: make([]common.Hash, 0), s: pendingTxSub}
//	api.filtersMu.Unlock()
//
//	go func() {
//		for {
//			select {
//			case ph := <-pendingTxs:
//				api.filtersMu.Lock()
//				if f, found := api.filters[pendingTxSub.ID]; found {
//					f.hashes = append(f.hashes, ph)
//				}
//				api.filtersMu.Unlock()
//			case <-pendingTxSub.Err():
//				api.filtersMu.Lock()
//				delete(api.filters, pendingTxSub.ID)
//				api.filtersMu.Unlock()
//				return
//			}
//		}
//	}()
//
//	return pendingTxSub.ID
//}
//
//// NewPendingTransactions creates a subscription that is triggered each time a transaction
//// enters the transaction pool and was signed from one of the transactions this nodes manages.
//func (api *PublicFilterAPI) NewPendingTransactions(ctx context.Context) (*rpc.Subscription, error) {
//	notifier, supported := rpc.NotifierFromContext(ctx)
//	if !supported {
//		return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
//	}
//
//	rpcSub := notifier.CreateSubscription()
//
//	go func() {
//		txHashes := make(chan common.Hash)
//		pendingTxSub := api.events.SubscribePendingTxEvents(txHashes)
//
//		for {
//			select {
//			case h := <-txHashes:
//				notifier.Notify(rpcSub.ID, h)
//			case <-rpcSub.Err():
//				pendingTxSub.Unsubscribe()
//				return
//			case <-notifier.Closed():
//				pendingTxSub.Unsubscribe()
//				return
//			}
//		}
//	}()
//
//	return rpcSub, nil
//}
//
//// NewBlockFilter creates a filter that fetches blocks that are imported into the chain.
//// It is part of the filter package since polling goes with eth_getFilterChanges.
////
//// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_newblockfilter
//func (api *PublicFilterAPI) NewBlockFilter() rpc.ID {
//	var (
//		headers   = make(chan *modules.Header)
//		headerSub = api.events.SubscribeNewHeads(headers)
//	)
//
//	api.filtersMu.Lock()
//	api.filters[headerSub.ID] = &filter{typ: BlocksSubscription, deadline: time.NewTimer(deadline),
//		hashes: make([]common.Hash, 0), s: headerSub}
//	api.filtersMu.Unlock()
//
//	go func() {
//		for {
//			select {
//			case h := <-headers:
//				api.filtersMu.Lock()
//				if f, found := api.filters[headerSub.ID]; found {
//					f.hashes = append(f.hashes, h.Hash())
//				}
//				api.filtersMu.Unlock()
//			case <-headerSub.Err():
//				api.filtersMu.Lock()
//				delete(api.filters, headerSub.ID)
//				api.filtersMu.Unlock()
//				return
//			}
//		}
//	}()
//
//	return headerSub.ID
//}
//
//// NewHeads send a notification each time a new (header) block is appended to the chain.
//func (api *PublicFilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, error) {
//	notifier, supported := rpc.NotifierFromContext(ctx)
//	if !supported {
//		return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
//	}
//
//	rpcSub := notifier.CreateSubscription()
//
//	go func() {
//		headers := make(chan *modules.Header)
//		headersSub := api.events.SubscribeNewHeads(headers)
//
//		for {
//			select {
//			case h := <-headers:
//				notifier.Notify(rpcSub.ID, h)
//			case <-rpcSub.Err():
//				headersSub.Unsubscribe()
//				return
//			case <-notifier.Closed():
//				headersSub.Unsubscribe()
//				return
//			}
//		}
//	}()
//
//	return rpcSub, nil
//}
//
//// FilterCriteria represents a request to create a new filter.
////
//// TODO(karalabe): Kill this in favor of ethereum.FilterQuery.
//type FilterCriteria struct {
//	FromBlock *big.Int
//	ToBlock   *big.Int
//	Addresses []common.Address
//	Topics    [][]common.Hash
//}
//
//// NewFilter creates a new filter and returns the filter id. It can be
//// used to retrieve logs when the state changes. This method cannot be
//// used to fetch logs that are already stored in the state.
////
//// Default criteria for the from and to block are "latest".
//// Using "latest" as block number will return logs for mined blocks.
//// Using "pending" as block number returns logs for not yet mined (pending) blocks.
//// In case logs are removed (chain reorg) previously returned logs are returned
//// again but with the removed property set to true.
////
//// In case "fromBlock" > "toBlock" an error is returned.
////
//// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_newfilter
//func (api *PublicFilterAPI) NewFilter(crit FilterCriteria) (rpc.ID, error) {
//	return "", nil
//}
//
//// UninstallFilter removes the filter with the given filter id.
////
//// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_uninstallfilter
//func (api *PublicFilterAPI) UninstallFilter(id rpc.ID) bool {
//	api.filtersMu.Lock()
//	f, found := api.filters[id]
//	if found {
//		delete(api.filters, id)
//	}
//	api.filtersMu.Unlock()
//	if found {
//		f.s.Unsubscribe()
//	}
//
//	return found
//}
//
//// GetFilterChanges returns the logs for the filter with the given id since
//// last time it was called. This can be used for polling.
////
//// For pending transaction and block filters the result is []common.Hash.
//// (pending)Log filters return []Log.
////
//// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getfilterchanges
//func (api *PublicFilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error) {
//	api.filtersMu.Lock()
//	defer api.filtersMu.Unlock()
//
//	if f, found := api.filters[id]; found {
//		if !f.deadline.Stop() {
//			// timer expired but filter is not yet removed in timeout loop
//			// receive timer value and reset timer
//			<-f.deadline.C
//		}
//		f.deadline.Reset(deadline)
//
//		switch f.typ {
//		case PendingTransactionsSubscription, BlocksSubscription:
//			hashes := f.hashes
//			f.hashes = nil
//			return returnHashes(hashes), nil
//		}
//	}
//
//	return []interface{}{}, fmt.Errorf("filter not found")
//}

// returnHashes is a helper that will return an empty hash array case the given hash array is nil,
// otherwise the given hashes array is returned.
//func returnHashes(hashes []common.Hash) []common.Hash {
//	if hashes == nil {
//		return []common.Hash{}
//	}
//	return hashes
//}
//
//// UnmarshalJSON sets *args fields with given data.
//func (args *FilterCriteria) UnmarshalJSON(data []byte) error {
//	type input struct {
//		From      *rpc.BlockNumber `json:"fromBlock"`
//		ToBlock   *rpc.BlockNumber `json:"toBlock"`
//		Addresses interface{}      `json:"address"`
//		Topics    []interface{}    `json:"topics"`
//	}
//
//	var raw input
//	if err := json.Unmarshal(data, &raw); err != nil {
//		return err
//	}
//
//	if raw.From != nil {
//		args.FromBlock = big.NewInt(raw.From.Int64())
//	}
//
//	if raw.ToBlock != nil {
//		args.ToBlock = big.NewInt(raw.ToBlock.Int64())
//	}
//
//	args.Addresses = []common.Address{}
//
//	if raw.Addresses != nil {
//		// raw.Address can contain a single address or an array of addresses
//		switch rawAddr := raw.Addresses.(type) {
//		case []interface{}:
//			for i, addr := range rawAddr {
//				if strAddr, ok := addr.(string); ok {
//					addr, err := decodeAddress(strAddr)
//					if err != nil {
//						return fmt.Errorf("invalid address at index %d: %v", i, err)
//					}
//					args.Addresses = append(args.Addresses, addr)
//				} else {
//					return fmt.Errorf("non-string address at index %d", i)
//				}
//			}
//		case string:
//			addr, err := decodeAddress(rawAddr)
//			if err != nil {
//				return fmt.Errorf("invalid address: %v", err)
//			}
//			args.Addresses = []common.Address{addr}
//		default:
//			return errors.New("invalid addresses in query")
//		}
//	}
//
//	// topics is an array consisting of strings and/or arrays of strings.
//	// JSON null values are converted to common.Hash{} and ignored by the filter manager.
//	if len(raw.Topics) > 0 {
//		args.Topics = make([][]common.Hash, len(raw.Topics))
//		for i, t := range raw.Topics {
//			switch topic := t.(type) {
//			case nil:
//				// ignore topic when matching logs
//
//			case string:
//				// match specific topic
//				top, err := decodeTopic(topic)
//				if err != nil {
//					return err
//				}
//				args.Topics[i] = []common.Hash{top}
//
//			case []interface{}:
//				// or case e.g. [null, "topic0", "topic1"]
//				for _, rawTopic := range topic {
//					if rawTopic == nil {
//						// null component, match all
//						args.Topics[i] = nil
//						break
//					}
//					if topic, ok := rawTopic.(string); ok {
//						parsed, err := decodeTopic(topic)
//						if err != nil {
//							return err
//						}
//						args.Topics[i] = append(args.Topics[i], parsed)
//					} else {
//						return fmt.Errorf("invalid topic(s)")
//					}
//				}
//			default:
//				return fmt.Errorf("invalid topic(s)")
//			}
//		}
//	}
//
//	return nil
//}
//
//func decodeAddress(s string) (common.Address, error) {
//	b, err := hexutil.Decode(s)
//	if err == nil && len(b) != common.AddressLength {
//		err = fmt.Errorf("hex has invalid length %d after decoding", len(b))
//	}
//	return common.BytesToAddress(b), err
//}
//
//func decodeTopic(s string) (common.Hash, error) {
//	b, err := hexutil.Decode(s)
//	if err == nil && len(b) != common.HashLength {
//		err = fmt.Errorf("hex has invalid length %d after decoding", len(b))
//	}
//	return common.BytesToHash(b), err
//}
